Is he a Minecraft fan?? If so, Minecraft has a very active modding community and that might be a great place to start.
To see it in action: https://www.youtube.com/watch?v=wrUHUhfCY5A&list=PLah_Dh8PIq... (the video's author, Direwolf20, had a good MOD pack including ComputerCraft).
Of course it's not directly creating a game, but perhaps a fun way to get introduced to programming.